The Terrestrial planets are thought to have formed by accreting solid planetesimals, all with about the same composition. What does this mean?
A) They were initially molten, forming an iron core first, then they accreted a silicate crust later.
B) They were initially molten, forming a silicate core first, then they accreted an iron crust later.
C) They were initially collections of solid particles, which melted and then differentiated into a high-density iron metal core and low-density silicate crust.
D) They were initially collections of solid particles, which melted and then differentiated into a high-density silicate core and low-density iron metal crust.

Question

Quizplus · Accepted Answer

The process described in option C accurately represents the current understanding of how terrestrial planets formed. They started as collections of solid particles (planetesimals) that, through accretion and the heat generated from impacts and radioactive decay, eventually melted. This allowed the denser materials, like iron, to sink towards the center, forming a high-density core, while the less dense materials, such as silicates, floated to the surface, forming a low-density crust.

The Terrestrial Planets Are Thought to Have Formed by Accreting